1. Field of the Invention
The present invention relates to a system for mirror-polishing the outer peripheral part of a semiconductor wafer and more particularly to a wafer polishing system for singly mirror-polishing, cleaning and drying the circumferential bevel surfaces and circumferential end surface of a semiconductor wafer, and the notch bevel surfaces (or orientation flat bevel surfaces) and notch end surface (or orientation flat end surface) provided in a notch part (or orientation flat) thereof.
In a semiconductor wafer, a cutaway for positioning, that is, a notch (hereinafter an explanation will be given taking a notch as an example) is formed, and then, bevel surfaces are formed by cutting off the square part of the edge over the outer peripheral part, that is, the overall contour, of the semiconductor wafer including a notch part. FIG. 1A is a plan view of a semiconductor wafer. FIG. 1B is a partial cross-sectional view of a semiconductor wafer W. FIG. 2 is a perspective view showing the periphery of a notch N in enlarged form. A pattern forming surface Sp, circumferential bevel surfaces Sb, and a circumferential end surface (a cylindrical surface forming the outer periphery) Sc of the semiconductor wafer in this state will cause generation of particles in the later process. These surfaces, including the notch bevel surfaces and notch end surface of the notch N, are mirror-finished by polishing.
In the semiconductor manufacturing process, formation and removal of a resist film are repeatedly done on the pattern forming surface Sp. In forming a resist film, resist is also coated outside the pattern forming surface Sp, namely on the circumferential bevel surfaces Sb and circumferential end surface Sc. If the outside resist film should not be removed or its removal should be incompletely done, particles from the residual resist film might adhere to the pattern surface, resulting in a drop in the semiconductor manufacturing yield. To prevent this, the resist film must be virtually completely removed by polishing, from not only the pattern forming surface but also other surfaces.
2. Description of the Related Art
A conventional wafer edge polishing system used for polishing (called edge-polishing) the circumferential bevel surfaces Sb, circumferential end surface Sc, notch bevel surfaces Sbn and notch end surface Scn as mentioned above, has been designed so that each polishing unit takes a sufficiently long polishing time in order to remove the resist film on every wafer virtually completely. In other words, in order to address an infrequent phenomenon, all wafers are polished for a long time. Therefore, despite improvements in polishing conditions, etc. made so far, it still remains difficult to further improve the average throughput in polishing work.